Hmm. It's there so I'm unclear why the linker is not resolving it. Though, it is odd there's an unresolved reference (the U) as well, Could this be from the magamblas lib?

Try linking with the verbose flag (-v) and let's see what's happening under the hood. Also, let's remove the "-R" flag since it might be trying to dynamically link the magma libs. Finally, add a second "-lmagma" in case magmablas references magma.